Tissue engineering is a technology adapted for culturing cells on scaffolds to form cell-scaffold complexes and applying them to fabricate tissues or organs for clinical use. According to the principle of tissue engineering, cells are isolated from a tissue of interest taken from a patient and cultured in a scaffold to form a cell-scaffold complex which is then implanted into the patient. Most definitions of tissue engineering cover a broad range of applications to the repair or replace of almost any human organ including, inter alia, artificial skin, artificial bones, artificial cartilage, artificial corneas, artificial vessels, artificial muscles, etc. To optimize the regeneration of tissues or organs, the provision of a scaffold similar to a bodily tissue may be the first priority. For use in tissue engineering, scaffolds fundamentally allow cells to adhere thereto and act as frames capable of supporting three-dimensional tissue formation. Also, scaffolds are required to be non-toxic and biocompatible as not to elicit blood coagulation and inflammatory reactions. That is, scaffolds for tissue engineering may be preferably biocompatible polymers which are friendly to adjacent tissues in the body and bio-adhesive without suffering from graft rejection. Biocompatible polymers are largely divided into natural polymers and synthetic polymers or into biodegradable polymers and non-biodegradable polymers. Examples of the natural polymers include protein-based polymers such as collagen, albumin, and amino acids; and polysaccharides and derivatives thereof, such as cellulose, agarose, alginate, heparin, hyaluronic acid, chitosan, etc.
Damaged thermal tissue, especially severely burnt skin is typically replaced with one of 1) autografts, obtained from the same individual to which they will be reimplanted, 2) allografts, which come from the body of a donor of the same species and 3) xenografts, which are isolated from individuals of another species. Autografts, although ideal, are problematic in that when a large area of the skin is injured, there are limited autografts available. Further, the acquisition of a thermal autograft causes another injury to the skin. As for allografts, they are used as a support that aids the migration and proliferation of cells around the injury rather than for purposes of eternal engraftment. A typical allograft is cadaver tissue or skin. Although immune responses may be avoided, there remains the problem of the shortage of allograft donors. To overcome such problems, active research has been directed toward the development of highly biocompatible natural or synthetic polymers suitable as scaffolds for the reconstruction of artificial skin.
To date, various crosslinking techniques have been extensively applied to natural polymers to produce biomaterials. The production of biomaterials by reacting chemical reagents, however, may be expensive because the reactions may have to be conducted under certain conditions in the presence of catalysts, and furthermore, the catalysts may be toxic. Further, there is always the possibility of the presence of impurities in the final product, which may, even should the chemical reagents be used in a very small amount, cause unanticipated side effects.
As a solution to this problem, radiation crosslinking for developing biomaterials has been studied. In radiation crosslinking, the absence of harmful chemicals including crosslinking agents, initiators and so on eradicates a post-radiation process of removing, for example, residual crosslinking agents or initiators. Also, radiation crosslinking can simultaneously guarantee both sterilization and crosslinking. In addition, this process enjoys the advantage of the crosslinking requiring no additional heat, making it possible to crosslink even materials which are in a refrigerated state, and readily controlling physical properties of the materials only with radiation doses, without changing compositions.
Beta-glucan (β-1,6-branched-β-1,3-glucan) is almost free of calories and has a generally recognized as safe statusin the United States of America following its approval by the FDA in 1983. It exhibits a variety of physiological activities including anticancer activity, wound healing, immunopotentiation, promotion of collagen biosynthesis, cell regeneration, high water retention, etc. As extensive research has proven the safety thereof for years, beta-glucan derived from Basidomycetes finds application in various fields including medicines, cosmetics, health foods, animal food additives, etc. In spite of its biocompatibility and various physiological activities, beta-glucan has not yet been developed or studied as a scaffold for tissue engineering thus far.
Beta-glucan with high biocompatibility and a variety of physiological activities is considered to exhibit no toxicity in the body. When radiation fusion technology is applied thereto, beta-glucan can be developed into a scaffold for tissue engineering which allows cells to readily adhere thereto and provides a biomimetic environment effective for the growth and differentiation of stem cells. There is therefore a need for the development of beta-glucan-based scaffolds in tissue engineering.